This invention relates to image development and more particularly relates to the dry development of latent images.
In the practice of image development a latent image pattern on a substrate is dusted or toned with finely divided attractable powder to produce a visible image. In most instances the attracted toner is subsequently transferred to a final image substrate and the latent image is again toned to provide multiple copies. The means for bringing the toner particles into contact with the latent image usually involves either immersing the latent image bearing surface in a bath of toner particles or toner particles are cascaded or flung toward the image bearing surface so as to impinge upon said surface.
A major problem encountered in the magnetic and electrostatic imaging processes is the unwanted adherence of toner particles in non-image areas of the surface carrying the latent image. The unwanted toner is termed "background" and its presence degrades the image quality of the copies produced by the imaging process. The development systems of the prior art place toner into contact with all areas of the surface carrying the latent image and thus provide the opportunity for toner particles in background areas to remain there due to one or more reasons, some not yet understood.
Accordingly, there is a need for a development system which brings toner particles to the latent image in large quantity yet gently so as to reduce the opportunity for the particles to adhere to the surface in background areas.